Conventionally, illumination of dwellings or establishments as well as the operation of various electrical equipment requires using electrical wiring for connections from the electrical outlets. The necessity of using such electrical wiring is a constraint which inconveniences its users. Specifically, outlets are rarely positioned in the most convenient location or in sufficient number, yet once they are used with the aid of extension cords, the user is disinclined to change the arrangement, even when it would be much preferable for example to prevent a multitude of cords traversing a room.
For supplying a place of business, greater flexibility should be possible as regards positioning various electrical office equipment such as a computer workstation, a telefax machine, a photocopier, etc. Setting up such an environment frequently requires a process of trial and error, and requires several attempts before a satisfactory configuration is achieved, which efforts would be greatly facilitated if connections by electrical wiring were not necessary.
It is known from French patent FR-B-2 717 614, to provide an illumination system in which lamp-type illuminating devices need no longer be connected by electrical wiring to the electrical distribution network or to any supply source.
Thus, a system for illuminating an area by means of a plurality of lamp-type illumination devices comprises lamp-type illuminating devices having no connecting electrical cords and which are disposed at any place within the area, and comprising means for inducing a magnetic field in the area as well as a plurality of means associated respectively with the lamp-type illuminating devices, each receiving the magnetic field and producing locally at each of the lamp-type illuminating devices an electrical supply energy. Thus, the said means for producing a magnetic field comprise at least one winding of electrical conductor disposed at the periphery of the area and traversed by an alternating current whereas each of the associated means comprises a coil composed of a plurality of windings between the terminals of which is induced an alternating voltage that supplies the associated illumination device with electrical energy.
However, for supplying electrical equipment other than lighting devices, this system has proven unsatisfactory for meeting all of the electrical current demands.
In particular, to produce a sufficient energy supply, it was necessary to provide a great number of windings and to use a rather high frequency. Consequently, impedance is thereby increased and, for a given electromotive force, the generated intensity will be low and out of phase with respect to the electromotive force.